BelovApi/BelovAPI/Controllers/DeleteUser.cs

using BelovAPI.BaseConnection;
using BelovAPI.ModelBase;
using Microsoft.AspNetCore.Mvc;

namespace BelovAPI.Controllers
{
    [Route("api/[controller]")]
    [ApiController]
    [ApiExplorerSettings(GroupName = "Действия с пользователем")]
    public class DeleteUser : Controller
    {
        ApplicationContext db = new ApplicationContext();
        [HttpDelete]
        public IActionResult Index(int id)
        {
            User user = db.User.FirstOrDefault(x => x.Id == id);

            db.User.Remove(user);

            db.SaveChanges();

            return Ok($"Вы успешно удалили {user}");
        }
    }
}